


A Promise, Kept

by Aria_Lerendeair



Series: Alec Lightwood Birthday Bash 2020 [5]
Category: Shadowhunters (TV), The Shadowhunter Chronicles - All Media Types, The Shadowhunter Chronicles - Cassandra Clare
Genre: Determined Alec Lightwood, Domestic Magnus Bane/Alec Lightwood, Emotional Hurt/Comfort, Excellent Husband Alec Lightwood, Happily Ever After, Hurt/Comfort, Immortal Husbands, Immortality Angst, Insecure Magnus Bane, M/M, Magnus Bane Deserves Nice Things, Magnus angst, parent malec
Language: English
Status: Completed
Published: 2020-11-29
Updated: 2020-11-29
Packaged: 2021-03-10 00:27:59
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,571
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27785245
Author URL: https://archiveofourown.org/users/Aria_Lerendeair/pseuds/Aria_Lerendeair
Summary: When Magnus opens up about one of his greatest fears, Alec makes him a promise.  That he'll stay, as long as Magnus wants him to.  When Magnus says forever, even though it's not possible?Alec makes some plans.
Relationships: Magnus Bane/Alec Lightwood
Series: Alec Lightwood Birthday Bash 2020 [5]
Series URL: https://archiveofourown.org/series/2016725
Comments: 19
Kudos: 365





	A Promise, Kept

**Author's Note:**

> Prompt by Anonymous: Magnus waking up in the middle of the night, checking up on their children, going back to bed and looking at his husband and having a little panic attack because he thinks he's not worthy of their love and thinking about how one day Alec will be gone and he'll be lonely once again.

  
When Alec woke up, he knew that something was off. He looked to the side of the bed that belonged to Magnus and sighed when he realized that it was empty. 

  
Pushing himself upright, he yawned and ruffled his hair before standing up. There weren’t many places that Magnus would go when he couldn’t sleep. Alec tugged his boxers on and went to go check on the kids. Both of them were still sleeping soundly and he relaxed. 

  
Alec huffed and looked around the house. He didn’t catch sight of Magnus and frowned. Normally Magnus came to watch the-

  
His eyes caught on Magnus, standing in the corner of the kid’s room, out of sight if he hadn’t been directly looking. Tears were streaming down his face and Alec closed his eyes and took a slow, deep breath. He stepped into the room and met Magnus’ eyes when they turned to him, fear-filled. 

  
Alec carefully took Magnus’ wrist and gave him a tug, pulling him gently out of the boy’s room, shutting the door behind them both, leading Magnus back to their bedroom. 

  
Magnus was following behind him, barely offering any resistance at all. Alec shut the door behind him and felt the soundproof wards settle over the both of them. He wrapped Magnus up in his arms, carefully. "Nightmare?“ he whispered. 

  
Magnus inhaled shakily, giving a brief shake of his head. "No.” 

  
“Okay,” Alec breathed, hugging Magnus again. “Want to tell me what did happen?" He felt Magnus hunch in his arms, his head shake coming harder this time. 

  
Alec hummed and kept Magnus pressed in close to him. It wasn’t hard to imagine what had gotten under his skin. There were a few things that always did it, consistently. "You know you’re an amazing father, right?” he whispered. “And that they love you so much? Almost as much as you love them?" 

  
Magnus hiccuped on a sob, wrapping his arms around Alexander, clinging tightly to him. 

  
"You’re the best father anyone ever could have asked for, Magnus. The best father, the best husband, the best leader,” Alec kissed the top of Magnus’ head and held him close, cradling Magnus against his chest. “I’m so lucky that I get to love you every single day." 

  
When those words provoked a sob and an even tighter grip from Magnus, Alec frowned in confusion. "Magnus?" 

  
Magnus sucked in a hard breath, tears falling faster. "I don’t deserve that. I don’t deserve any of you. I’m so lucky that I have you, all three of you, but I know…” A small, weak whine escaped him and he hated himself for it. He hated how weak he was. “I know one day I’m going to be alone again." 

  
Alec stilled, keeping his arms wrapped around Magnus, nuzzling into his temple. _"Magnus."_

  
"One day,” Magnus whispered, his voice weak and muffled against Alec’s shoulder. “One day, Max is going to live his own life. Find love, and happiness. And you and Rafe will be... will…” Magnus swallowed, choking on the words as another sob cracked in his throat. 

  
Alec tightened his arms around Magnus, breathing out hard. “Magnus, love, you can’t do this to yourself. You can’t. You’ve told me that. More than once, in fact." 

  
Magnus gave a small nod. "I know,” he whispered. “I know, Alexander, that we have to appreciate the time that we have together right now, and focus on the here and now. I _know."_ He closed his eyes and took a deep breath. "But I’m so scared. I’m terrified. This kind of happiness has a price, Alec. It always does. And that price won’t come until… _after."_

  
Alec sucked in a quiet breath and breathed out against Magnus’ temple. "I think you’ve paid enough of those kinds of prices in your life, Magnus." 

  
Magnus closed his eyes, leaning against Alec, the firm heartbeat under his ear. "It’s okay,” he said, his voice soft, even though it wasn’t. Even though it never, ever would be. “I’ll pay this one. Gladly. If it means I get to have you all, now? I’ll pay whatever the price is for this." 

  
Alec hummed and held Magnus tighter, even as his tears started to fade. He took a deep breath and pulled back, leaning back so their eyes could meet. Magnus was already trying to piece himself back together, to hide the pain that was going to grow every single day. "What would you have me do?" 

  
Magnus gave a small laugh and pressed his forehead against Alec’s. "There’s nothing you can do, Alexander. And that’s all right. I promise that it is." 

  
Alec shook his head. "No. It isn’t. Not if it means you are going to be hiding this for the next several decades, Magnus." 

  
Magnus sucked in a small breath and sighed. "I shouldn’t have said anything,” he explained, opening his eyes again. “I’m sorry, Alec, I didn’t-" 

  
"Hey, no, none of that,” Alec corrected. _“Husbands._ We carry our burdens together, remember? And that includes this one." 

  
"There’s no burden for you to carry here, my darling,” Magnus said, his voice soft as he cupped Alec’s cheek. 

  
Alec frowned and kissed Magnus, a soft and swift press of their lips together. “Tell me what I can do,” he ordered again, his voice soft and adamant. 

  
_“Stay,”_ Magnus breathed, his voice soft and only a fraction desperate. “Stay for as long as you are able, as long as you can, Alexander. Stay and let me have this for as long as is possible." 

  
Alec swallowed and stared Magnus down, meeting his fearful golden eyes with a smile. "That’s an easy promise to make, Magnus,” he whispered. He pulled his husband back into his arms and held him tight. “I’m going to stay as long as you want me." 

  
"Forever, then,” Magnus whispered, closing his eyes. “Because I’m never going to not want you, Alexander. Not ever." 

  
Alec tightened his arms around Magnus and held him even tighter. Once he was sure that Magnus had drifted off again, Alec took a deep breath. "I’m not going to let you pay the price this time, Magnus. It’s my turn. I promise. I’m not going to leave until you want me to.” 

  
When Magnus shifted closer at the sound of his voice, Alec steeled himself and took a deep breath, holding his husband as tight as he dared. He would keep his promise, and nothing, no one, was going to stop him. 

  
~!~ 

  
It took a year. 

  
A full year, for him to keep his promise.

  
To find the answers, to find the how. To find the price that he would have to pay for the chance, alone, let alone the toll he would pay for immortality itself. 

  
The price was high - because there was always a cost. His runes. His Nephilim blood. He would no longer be what he had been born as. He would no longer have the purpose that had been his since before he knew what those words had meant. 

  
But in return? 

  
In return, Magnus would not have to pay the price for being happy. And that made the decision easy, for Alec. 

  
Once it was done, and finished, all he had to do was tell Magnus. To tell him that his promise would be kept. That he was going to stay as long as Magnus wanted him to. However long that might be. 

  
Alec made sure to get a babysitter for the evening, and ordered them dinner so they could share. After that, it was waiting for Magnus to get home, and once he was? To have a conversation about what he had done. 

  
When Magnus walked through the door, a delighted grin on his face at the sight of the dinner table set for him, Alec’s chest tightened and he knew he’d made the right decision. He would spend a thousand years putting a smile like that on Magnus’ face. Maybe more. 

  
“Alexander, what’s all this?” Magnus asked, looking around curiously. "I didn’t forget an anniversary, did I?“ 

  
"No,” Alec said, shaking his head, tugging Magnus in for a kiss hello. "You didn’t forget anything. This is just something I wanted to do for you. Because I made you a promise, a year ago, and tonight? I’m able to keep it.“ 

  
Magnus raised his eyebrows and then wrinkled them in confusion. "A promise? What kind?” 

  
Alec took a deep breath and took Magnus’ hands, giving them a gentle squeeze. "I promised you that I would stay for as long as you want me,“ he said, his voice soft. A quick spasm of pain chased its way across Magnus’ face before he was neutral again and Alec’s heart broke at the sight. He leaned in and rubbed their noses together. "I’m keeping that promise, Magnus.” 

  
“Alexander,” Magnus started, his voice hoarse. "I know-“

  
Alec leaned in and kissed him, soft and gentle, before he pulled back and took a deep breath. Exhaling hard, he let the glamour on his eyes fall. He met Magnus’ eyes and smiled at him, tentatively. “I’m yours, Magnus,” he whispered, watching tears gather in Magnus’ eyes. _“Forever.”_

  
Alec waited, hoping, praying to an Angel that would no longer hear him, that he hadn’t made the wrong decision. When Magnus yanked him into a tearful kiss, hard and desperate, he clung to Magnus as tight as he dared. 

  
This had never been Magnus’ price to pay.   
  


**Author's Note:**

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